How to size a drop hitch for a level tow
Measure tow vehicle receiver height and trailer coupler height, then pick the drop (or rise) that lets the trailer sit flat. Quick reference table included.
Measure two things: the height from the ground to the inside top of your receiver tube, and the height from the ground to the bottom of your trailer coupler when the trailer is loaded and level. The difference is the drop or rise you need.
Trailer coupler lower than the receiver: you need a drop. Higher: you need a rise. Most pickup-and-trailer setups need somewhere between 4 and 10 inches of drop.
Why “level” matters
A trailer that noses down throws weight forward, lightens the truck’s rear, and makes braking unstable. A trailer that noses up reduces tongue weight, lets the trailer wag at speed, and is the most common cause of trailer sway. Aim for the trailer frame sitting parallel to the ground when loaded.
For weight-distribution hitches, level is also what the WD spring bars are designed around. Run them on a non-level setup and they don’t transfer load correctly.
The measurement, in order
Park truck and trailer on the same flat surface. Driveway slope makes the math wrong.
Load the trailer the way you actually tow it. Empty utility trailers sit lighter on the front and the height will be off.
With the trailer disconnected but on its jack at towing height, measure from the ground to the bottom flat surface of the coupler ball socket. Call that A.
Measure from the ground to the inside top of your receiver tube opening. Call that B.
If B is bigger than A, you need a drop of (B minus A). If A is bigger than B, you need a rise of (A minus B). Most ball mounts can be flipped to give either drop or rise from the same part.
Quick reference by receiver height
Most modern trucks have a receiver between 18 and 26 inches off the ground. Bumper-pull trailers typically have couplers at 17 to 22 inches.
| Receiver height | Coupler at 17 in | Coupler at 19 in | Coupler at 21 in |
|---|---|---|---|
| 18 in | 1 in rise | 1 in drop | 3 in drop |
| 20 in | 3 in rise | 1 in rise | 1 in drop |
| 22 in | 5 in rise | 3 in rise | 1 in rise |
| 24 in | 7 in drop (flipped) | 5 in drop | 3 in drop |
| 26 in | 9 in drop | 7 in drop | 5 in drop |
| 28 in | 11 in drop | 9 in drop | 7 in drop |
Lifted trucks push receiver heights past 28 inches and need adjustable-shank mounts (Andersen, BulletProof, GenY) that can drop 10 inches or more.
Ball mount versus adjustable drop hitch
A fixed ball mount is a single piece of steel with a set drop and a welded ball. Cheap, simple, and only fits one trailer height.
An adjustable drop hitch has a vertical shank with stacked holes and a clamped or pinned ball platform. Useful if you tow multiple trailers or share a truck with someone whose trailer doesn’t match. Models from B&W, Andersen, Curt, and GenY cover most use cases. Expect to spend $150 to $450 for a quality adjustable.
Aluminum adjustables (Andersen Rapid Hitch and similar) are lighter to wrestle around than steel and don’t rust. Steel handles higher tongue weights, generally 14,000 lb plus.
Ball size and tongue weight matter too
The drop is one of three things to match. The others:
Ball size. 1-7/8, 2, 2-5/16, or 3 inch. Wrong size lets the coupler pop off under load. The trailer coupler is stamped with the correct size.
Class rating. The ball mount, receiver, and ball all have GTW (gross trailer weight) and tongue weight ratings. The weakest link is your real rating.
Don’t buy a 2-5/16 ball rated to 10,000 lb if your receiver is Class III rated to 6,000. The truck’s limits don’t change.
Rough numbers from common setups
A stock F-150 SuperCrew with a 5-foot bed and standard suspension has a receiver around 22 inches up. Towing a 17-inch coupler utility trailer needs about 5 inches of rise. Towing a 21-inch coupler enclosed trailer needs about 1 inch of rise.
A 3/4-ton diesel (Silverado 2500HD, Ram 2500, F-250) sits taller. Receivers commonly land at 24 to 26 inches, so a 5 to 7 inch drop is standard on these trucks.
A leveled half-ton or a 4-inch lift adds 2 inches or more to receiver height. Re-measure after suspension work.